The use of microwave energy to reheat or cook food products for consumption is increasing. With certain food products, particularly those with an exterior crust, the result often is not acceptable, since the crust is not crispened.
It is well known, for example, from U.S. Pat. No. 4,641,005, that a thin metallic film may be employed to convert a portion of microwave energy incident thereon into thermal energy, and that such thermal energy may be employed to effect crispening or browning of the crust of a foodstuff being heated by microwave energy.
A number of applications of such technology have been proposed but, as a general rule, the thermal energy production has been one-dimensional, in the sense that the same thermal output is obtained from all the regions of the packaging structure where the thin metal film is located.
Having regard to the nature of certain food products, this uniform heat generation may be unsatisfactory and may lead to uneven cooking of the food when exposed to microwave radiation, as typically occurs with pizza.